The actress told the Daily Record: "I couldn't do the first 10 episodes when they moved [to Greenock], because I had my tour booked and it clashed.

"But when they knew I would like to come back, they brought me in a different role. So they have put me in as head of the pupil referral unit, which is where all the naughty kids go.

"She is the ultimate disciplinarian so, if they step out of line, she has them running around the school grounds like it's some kind of military base. It's quite funny, really. I do think there is a comedy element to it."

Speaking of her singing career, which at one point saw her working with Simon Cowell at Sony/BMG, Peace revealed why she finds it better having her own independent label.

Peace said: "I'm happier, absolutely. We have complete control and it is literally just me, my manager and a lady who does the PR. It is brilliant. I would rather it was this size with me having control than being huge and losing all of that.

"We have released it on our own record label. I think that unless you get in the charts, Joe Public thinks you are not a success. But the way I measure success is that I don't have to get another job to supplement my mortgage. Success to me is having a job you love. That's what's happening.

"We are coming up for our third tour next March, dates are selling out and it's got bigger again. We play the Fruitmarket in Glasgow, and then tour Australia.

"There is so much out there now. It is not completely owned by the big label. There is a way of doing your own thing, and I think a lot of people want to go and find new music. It is not just about people finding the same song."

Peace also said of Cowell: "I've met him a couple of times since the whole experience, and he's a gent. He always remembers your name."